I feel stupid for requesting something like that (because the ingame music rocks and who turns sound effects off?) but when I tried to turn off the music, I could only set the volume to 1 as a minimum. It would be nice if the minimum was 0 so the game music and other sources don't mix.
Before anybody starts throwing stones: Was was working with the leveleditor and listening to mp3s. And when I tested the maps I just happend to notice that you can't mute the music in Xenonauts.
It just doesn't feel right to have an ingame volume control panel without the possibility to mute something.